Compressor cooling system



Nov. 19, 1968 K. sAHLE COMPRESSOR COOLING SYSTEM 2 Sheets-Sheet 1 Filed Nov. 14, 1966 l INVENTOR //V/E 54/7/5 ATTORNEY NOV. 19, 1968 K, SAHLE 3,411,315

COMPRESSOR COOLING SYSTEM Filed Nov. 14, 1966 I 2 Sheets-Sheet 2 BYWZM ATTO? N EY United States Patent O 3,411,315 COMPRESSOR COOLING SYSTEM Knute Sahle, West Manchester Township, York, Pa., assignor to Borg-Warner Corporation, Chicago, Ill., a corporation of Illinois Filed Nov. 14, 1966, Ser. No. 593,930 1 Claim. (Cl. 62-224) ABSTRACT OF THE DISCLOSURE A multi-cylinder refrigeration compressor including means for injecting liquid refrigerant into the suction gas. The refrigerant is mixed with the gas in an elongated tube which includes a temperature sensor to control the amount of liquid refrigerant supplied.

This invention relates to gas compressors and more particularly to multi-cylinder, refrigeration compressors with means for cooling for the suction gas entering the cylinders.

A conventional, high capacity reciprocating compressor for refrigeration systems usually includes several cylinders arranged in various configurations, such as in-line, multiple V, multiple W, or radial. In addition, a typical method of controlling the capacity of the compressor is to maintain one or more cylinders fully loaded while selectively unloading the remaining cylinders. While various unloading procedures are known, it is conventional in large compressors to provide a mechanism for lifting the suction valves to prevent any work from being performed on the gas pulled into the unloaded cylinders.

With this type of capacity control arrangement, high temperature operating conditions are often encountered in the vicinity of ythe fully loaded bank. These conditions have been traced directly to the over-heating of a deck or wall surrounding the fully loaded cylinder(s) in the suction chamber. Thus, when the incoming suction gas comes in contact with the wall, several degrees of superheat are added to the gas with the corresponding loss in efficiency.

The present invention provides a liquid, or preferably wet gas, injection cooling system adapted to entrain cold refrigerant into the stream of superheated suction gas en route to the cylinders. The refrigerant then abstracts heat from the superheated suction gas and reduces the operating temperature of the compressor. While refrigerant injection systems are known in the art, the present invention utilizes an effective, low-cost assembly which insures adequate mixing of refrigerant with the incoming suction gas and further provides accurate temperature control.

It is therefore a principal object of the invention to provide an improved compressor cooling system.

Another object of the invention is to provide a refrigerant injection system which assures thorough mixing and intimate contact of the refrigerant with the suction gas.

Another object of the invention is to provide a compressor cooling system with automatic temperature control which has rapid response characteristics capable of adapting to sudden changes in the temperature of the entering suction gas.

Additional objects and advantages will be apparent from the following detailed description taken in conjunction with the drawings wherein:

FIGURE 1 is a cross-section view illustrating a preferred embodiment of the invention',

FIGURE 2 is a cross-section taken along the plane of line 2--2 of FIGURE l; and

FIGURE 3 is a detailed isometric view of the improved desuperheater or refrigerant injection assembly.

3,411,315 Patented Nov. 19, 1968 ice Referring now to the drawings, the main housing 10 has a generally W-shaped cross-section and in the particular embodiment shown is provided with three banks of two cylinders each. It should be understood, however, that the invention is applicable to other multi-cylinder configurations and that the description herein should not be limited to the particular arrangement illustrated. The housing 10 is divided by a wall 11 into an upper portion containing cylinders 12 and a suction chamber 13, and a lower, crank case portion enclosing the crank shaft and connecting rods 14 connected at 15v to vdrive the pistons 16. The crank shaft is driven by a motor or other suitable means (not shown). The compressor heads 17 are secured directly to the upper wall 18 of housing 10; and the space between the upper and lower wall constitutes a suction gas chamber supplying gas from the evaporator to all of the cylinders. The compressor heads 17 are interconnected by a discharge gas manifold (not shown) leading to a common discharge line.

The gas working spaces 19 are enclosed by a valve plate 20 received within recesses 22 in the upper wall of the housing, said valve plates being adapted to hold down an annular suction valve 23 in spring contact with the upper edge of each cylinder. The discharge valves 24, also in the form of annular discs, are positioned in overlying relationship with a series of openings 24 in valve plates 20. Each discharge valve is biased downwardly against the valve plate by means of springs 26 interposed between the compressor heads and the valve plates. On the suction stroke of the pistons, the radial innermost portion of the suction valves are lifted to permit gas from the suction chamber 13 to enter the gas working spaces 419. On a compression stroke, the suction valve closes; and upon reaching a predetermined pressure, the gas is effective to open the discharge valve 24 and flow into the space 27 enclosed by the compressor heads.

As best shown in FIGURE l, the center bank of cylinders is surrounded by a generally U-shaped, upstanding wall 28 which extends between the upper wall 18 and the dividing wall 11. Wall 28 separates the suction chamber 13 into two parts, the first, 13a, supplying gas to the two outboard cylinder banks and the second, 13b, supplying gas to the center cylinder bank. The center bank of cylinders is the one whose cylinders are fully loaded during operation, while the cylinders in the two outboard banks are provided with valve lifting mechanisms (not shown) for selectively varying the capacity of the compressor.

Refrigerant gas from the evaporator (not shown) is introduced into the suction chamber 13 through a suction line fitting 30 in one of the side walls of the housing 10. The gas initially enters the first section 13a of the suction chamber in a zone which is closest to one of the outboard banks; and then it flows around wall 28 to the other outboard bank following the path of arrows 29.

The flow path to the second section 13b of the suction chamber is defined, in part, by the desuperheater assembly, generally designated at A. The desuperheater assembly A comprises an elongated mixing tube 32 having one end cooperating with an opening in wall 28 and the other end extending well into the first section 13a of the suction chamber. The refrigerant (coolant) is supplied from a source (not shown) by means of a supply conduit or tube 33 which has a 180 return bend 34 at the discharge end so as to direct the coolant ejected through nozzle 35 in the same direction as the suction gas flowing through the mixing tube.

While liquid refrigerant may be used as the coolant, it may be more desirable to use wet gas in certain applications. In a preferred embodiment, liquid refrigerant at condenser pressure is supplied first through a heat exchange coil (not shown) located in the lower portion (sump) of the crank case to cool the oil in the sump.

The coolant reaching tube 33 is a wet gas but still has considerable cooling capacity for the low pressure, super heated suction gas when it comes in contact therewith.

The controls for maintaining proper temperature of the suction gas are preferably located in a well 36 at the exit end of the gas mixing tube 32. A temperature sensing bulb 37 is located within the well and is adapted to operate a temperature responsive valve 38 located in the coolant supply line.

Operation After entering the first section 13a of the suction chamber, the gas flows around wall 28, being constrained by the bight portion of said wall to ow along a path leading to the other outboard cylinder bank. Part of the gas passes into the entrance end of the mixing tube 32 where it cornes in contact with the stream of wet refrigerant gas being supplied to the same end of the tube through the nozzle 35 at the end of the coolant delivery tube. In flowing through the tube 32, adequate mixing is insured between the coolant and the suction gas; and the mixture ows out the exit end of the tube into suction chamber 13b which feeds the center bank of cylinders. Accurate control for this system is obtained by locating the temperature sensing element 37 for valve 38 at the eXit end of the mixing tube so that the over-all temperature of gas which enters suction chamber 13b can be controlled within close limits.

While this invention has been described in connection with a certain specific embodiment thereof, it is to be understood that this is by way of illustration and not by way of limitation; and the scope of the appended claim should be construed as broadly as the prior art will permit.

What is claimed is:

1. In a multi-cylinder compressor including a housing providing gas working spaces, means defining a suction gas chamber for supplying gas to be compressed to said gas working spaces, and piston means for compressing said gas, the improvement comprising means defining an elongated passageway through which said gas to be compressed is constrained to flow en route from said suction gas chamber to one of said gas working spaces, said passageway having an entrance end and a discharge end, said discharge end communicating with said one gas working space; means for supplying a coolant to said passageway entrance end in the same direction as gas flow, whereby said coolant is maintained in intimate contact with said gas stream for a suflicient length of time to abstract heat therefrom; and means for regulating the flow of refrigerant into said entrance end in response to the temperature of mixed gas and coolant leaving said discharge end.

References Cited UNITED STATES PATENTS 3,006,163 10/1961 Koolker 62--505 XR 3,163,999 l/l965 Ditzler 62-505 XR 3,226,949 l/l966 Gamache 62-505 XR 3,300,997 1/1967 Kocher 62-505 XR MEYER PERLIN, Primary Examiner'. 

